A conventional rotary die cutter comprises a magnet roller, an anvil roller arranged opposite to the magnet roller, a flexible die which is magnetically mounted on the magnet roller, and a sheet feed unit supplying a sheet one by one between the magnet and anvil rollers, in which the sheet supplied from the sheet feed unit is punched out by the flexible die (the term “punch” may be used to denote not only its original meanings but also “emboss”, “score”, “perforate” and so on. The same applies hereinafter.) while the sheet is conveyed by the magnet and anvil rollers (See, for example, JP 2003-237018 A and JP 2012-161859 A).
In such rotary die cutter, each of the magnet and anvil rollers forms large diameter portions (generally referred to as “bearers”) at both ends thereof and a small diameter portion at intermediate portion thereof, and the small diameter portion extends between the large diameter portions. Then, when the magnet and anvil rollers contact with each other at their bearers, a gap corresponding to a height of the die is formed between the small diameter portions of the magnet and anvil rollers.
Then the die is magnetically mounted on the periphery of the small diameter portion of the magnet roller, and the bearer of the magnet roller and the bearer of the anvil rollers are pressed against each other in order to prevent a failure of punching by keeping the gap between the magnet and anvil rollers constant, and then the punching operation is performed.
However, according to such configuration, one type of the die whose height corresponds to the gap can only be used because the size of the gap between the magnet and anvil rollers cannot be changed. Therefore, a punching operation using various types of dies whose heights are different from each other is considerably inconvenient because a dedicated rotary die cutter is required for each type of the die.